Contactless ignition devices



Jan. 10, 1967 TOSHIYUKI sA s l ETAL ,2 7,

y 1 CONTACTLESS IGNITION DEVICES Filed July 8. 1964 5 Sheets-Sheet 1 IHUEnTofiS Tod'fiyuKi SasaKi yoshlsada ATTORNEY 1967'} TOSHIYUVKIV SASAKI ETAL 3,297,009

CONTACTLESS IGNITION DEVICES Filed July 8. 1964 3 Sheets-Sheet 2 ATTORNEY Jan. 10, 1967 Filed July 8. 1964 3 Sheets-Sheet 5 N g 'wsg km M 6% N 39 m &, 3 R m 5 1w 1 g Q VT Q' 3.51 A Mul r I N g 12.: Q

ATTORNEY United States Patent 3,297,009 CONTACTLESS IGNITIQN DEVICES Toshiynlri Sasaki and Yoshisada Takaknra, Hitachi-sin,

Japan, assignors to Hitachi, Ltd., Tokyo, Japan, a corporation of Japan Filed July 8, 1964, Ser. No. 381,045 Claims priority, application Japan, July 10, 1963, 38/50,951 6 Claims. (Cl. 123-148) The present invention relates to new and improved ignition devices of the contactless type which are adapted for ignition of engines of automotive vehicles and the like.

As rotational speeds of the engines of automotive vehicles get higher, the trend is towards the use of a contactless ignition device having transistors therein in lieu of a heretofore generally employed system in which the primary current of an ignition coil is interrupted by the contact of an interrupter. In the transistor-type'ignition device, a magneto generator or the like of small size rotating in interengaging relation with the engine revolution is utilized to detect the igniting position of the engine. The operation of a transistor connected with the ignition coil of the engine is controlled by the output of the generator for thereby producing an ignition pulse in the current flowing through the ignition coil. However, such transistor-type ignition device is still defective in that the output of the magneto generator incorporated therein is not stabilized until the number of revolutions of the engine increases up to a certain value. Additionally its output wave forms vary widely at low speed and high speed revolutions of the engine, with the resultant difiiculty of detection or regulation of the proper igniting position of the engine.

In an ignition device intended for service as described above, the widely acknowledged requisiteis its capability to advance the time of production of the ignition current pulse with the increase in the rotational speed of the engine. A further difiiculty encountered with the prior ignition device has been that it is extremely difficult to dispose an automatic time of ignition advancing means at a location adjacent the igniting position detecting means for simultaneous operation therewith. Therefore, ignition lag during the high speed revolution has more or less been inevitable and neglected in practical use, resulting in frequent failures of ignition and loss of fuel.

The present invention intends to obviate the abovedescribed drawbacks of prior contactless ignition devices, and has for its first object to provide a contactless ignition device in which new and improved igniting position detecting means using a Hall element, are provided. The Hall element develops a definite electromotive force irrespective of the rotational speed of the engine. For this purpose, the Hall element is disposed in a magnetic field rotating in association with the revolution of the engine and is arranged such that the magnetic flux, in conjunction with a variable magnitude control current, automatically varies the time of production of the ignition pulse to thereby advance the igniting position of the engine with advancing speed. The Hall element is in effect connected with an ignition coil through ignition control means comprised by an igniting transistor so as to intermittently supply a definite amount of current in the ignition pulse produced in the ignition coil irrespective of the rotational speed of the engine.

Another object of the present invention is to provide a contactless ignition device in which an electric generator whose output is variable in proportion to the engine revolution, is connected across the control current terminals of the Hall element. By this arrangement, the electromotive force of the Hall element is thereby controlled for automatically advancing the igniting position in association with increases in the rotational speed of the engine.

A further object of the invention is to provide a contactless ignition device in which output terminals of the hall element are connected with igniting position regulating means having a pair of transistors whose conducting state abruptly varies at a voltage more than a predetermined value. This insures the positive operation of the ignition control means controlling the igniting transistor by the output voltage of the Hall element, and facilitates the setting or adjustment of an initial igniting position by the igniting position detecting means.

According to the present invention, there is provided a contactless ignition device adapted for automotive vehicles and the like comprising igniting position detecting means having a Hall element disposed in a magnetic field rotating in association with the revolution of the engine. The magnetic flux, in conjunction with a variable magnitude control signal, automatically varies the igniting position of the engine. For this purpose, an igniting transistor, an ignition coil energized by said igniting transistor, and ignition control means are connected with the output terminal of said igniting position detecting means for controlling said igniting transistor therethrough.

According to another feature of the present invention, there is provided a contactless ignition device of above character, further comprising igniting position advancing means having an electric generator whose output is variable in proportion to the revolution of the engine. This electric generator is connected across the control current terminals of said Hall element in said igniting position detecting means for supplying the variable magnitude control current thereto to thereby control the output of said igniting position detecting means.

According to a further feature of the present invention, there is provided a contactless ignition device of above character, in which said Hall element in said igniting position detecting means is held between supporting blocks in a maner such that a closed magnetic circuit is formed therethrough with pole pieces provided in a rotary body rotating in synchronism with the revolution of the engine. The pole pieces are so mounted on the rotary body that they are brought during rotation to a position opposite a set of supporting blocks of low magnetic reluctance material between which the Hall element is supported.

According to a still further feature of the present invention, there is also provided a contactless ignition device of above character, further comprising igniting position regulating means having a pair of transistors Whose conducting state is abruptly varied by a voltage appearing at the output terminal of the igniting position detecting means, and pulse generating means for supplying the output of said igniting position regulating means to the ignition control means for thereby controlling the igniting transistor.

There are other objects and particularities of the present invention which will become obvious from the following description when considered with reference to the accompanying drawings, in which:

FIG. 1 is a schematic electrical circuit diagram of an embodiment of a contactless ignition device according to the present invention;

FIG. 2 is a schematic diagram showing the principle of the operation of a Hall element incorporated in an igniting position detecting means of the present invention;

FIG. 3 is a plan view showing the structure of the igniting position detecting means;

FIG. 4 is a graphic representation of a relation between an electromotive force of the Hall element and the revolving angle of a rotating magnetic field;

FIG. is an electrical circuit diagram of another embodiment of the present invention; and

FIG. 6 is a graphic representation of the voltage revolving magnetic field angle characteristic of the Hall electromotive force.

The invention will now be described with reference to the drawings. First referring to FIG. 1, reference numeral 1 denotes automatic igniting position advancing means which includes a small-sized electric generator 2 whose output is variable in proportion to the revolution of the engine. The generator 2 has its power generating coil 3 connected with a rectifier 4 and smoothing filter circuit 5. Reference numeral 6 designates means for detecting the igniting position. As best shown in FIGURE 3, the igniting position detecting means 6 includes a rotor 7 designed for rotation with the engine, and in which permanent magnets 8 and magnetic poles 9 are alternately annularly arranged and supported by an annular member 10 of nonmagnetic material. On opposite sides of one of the permanent magnets 8 in the rotor 7, there are provided pole pieces 11 and 12 which extend radially outwardly through the annular member 10. A Hall element is held between supporting blocks 13 and 14 of low reluctance magnetic material. The blocks 13 and 14 are disposed in a manner such that maximum lines of magnetic flux cut across the Hall element 15 when the pole pieces 11 and 12 of the rotor 7 come to the position just opposite the magnetic supporting blocks 13 and 14 during the rotation of the rotor 7.

As best seen in FIGURES 1 and 2, the Hall element 15 is provided with output terminals 16 and 17 and control current terminals 18 and 19. One of the control current terminals 18 is connected to the other terminal by' way of a smoothing circuit 5, a battery 20, and a rheostat 21. The output terminal 16 is connected to the emitter'22e of a transistor 22, while the output terminal 17 is connected to the base 22b of the transistor 22.

Reference numeral 23 designates ignition control means which includes therein a Zener diode 24. The Zener diode 24 has its cathode connected with the collector 220 of the transistor 22 and its anode connected with the base 26b of a first control transistor 26 by way of a resistor 25. There is also provided a second control transistor 27, the base 27b of which is connected with the collector 26s of the transistor 26 by way of a resistor 28, while the emitter 27e is connected with the collector 270 by way of the battery 20, and a resistor 29.

The ignition semi-conductor comprised by a device of the present invention has an igniting transistor 30, the base 30b, collector 30c and emitter 30c of which are connected with the resistor 29, with the battery and with the battery 20 by way of the primary coil 31 of an ignition coil 33, respectively. The secondary coil 32 of the ignition coil 33 is connected with an ignition plug 34. A protective diode 35 for the igniting transistor 30 is connected across the emitter 30c and the collector 30c and a condenser 36 is connected in parallel therewith.

In the ignition device of the present invention with the arrangement as described above, a Hall electromotive force V appearing across the output terminals 16 and 17 of the Hall element 15 in the igniting position detecting means 6 is given by the product of a control current I and a magnetic flux density B of the magnetic flux cutting across the Hall element 15, as shown in FIG. 2. Thus,

where:

V =Hall electromotive force Bzmagnetic flux density l =control current R =Hall constant d=thickness of Hall element f(/b)=correction factor variable by the shape of Hall element r 4 Therefore, it will be understood that, the output of the igniting position detecting means 6, which controls the 'transistors 26 and 27 of the ignition control means 23 and hence the igniting positions of the engine, is set at a predetermined voltage V, by appropriate adjustment of the resistor 21. The igniting position can be determined by the relation between the control current I and the density B of magnetic flux cutting across the Hall element 15 obtained from the above formula of the Hall electromo- I (0) =magnetic flux as a function of angular relation between pole pieces 11, 12 and supporting blocks 13, 14

Current generated in the generating coil 3 of the electric generator 2 is rectified by the rectifiers 4 and is smoothed in the smoothing filter circuit 5. This current is then applied to the Hall element 15 through the control current terminals 18 and 19 with which the battery 20 is also connected. Therefor, as the amount of charges in the smoothing condenser C of filter 5, increases or decreases in proportion to the output of the generating coil 3 the control current I applied to the Hall element will also increase or decrease proportionally.

It will therefore be understood that, by arranging the control current I for the Hall element 15 in a manner that it increases with the increase in the number of revolutions of the engine, the normally required Hall electromotive force ca'n'be generated with a fringe magnetic flux density of lower value than that required with revolution at low speed. In other words, the predetermined voltage V can easily be developed even when @(6) in the above formula involves a greater angular relation between the pole pieces and the supporting blocks, and thus the igniting position can be advanced by an amount of 0 which is the angular difference therebetween.

Suppose, for example, that the igniting position is at 0 as shown in'FIG. 4 at the number of revolutions A (r.p.-m.) of the engine. As the engine is revolved at a faster rate, the output of the generating coil 3 is increased to correspondingly increase the control current I flowing to the Hall element 15. As a result, from the relation B= I (6)/S, the Hall element 15 can develop the normally required Hall electromotive force V at a position 0 which is advanced ahead of the angle 0 Then, by proper arrangement of the breakdown voltage of the Zener diode 24 in the ignition control means 23 so that the voltage V has a greater value than the Zener voltage, the Zener diode 24 in the ignition control means 23 is urged to its conducting state by the Hall electromotive force V of the Hall element 15. This occurs upon the pole pieces 11 and 12 of the rotor 7 of the igniting position detecting means 6 being brought to a position just a little ahead of the position opposite the supporting blocks 13 and 14 for the Hall element 15 during the ignition of the engine at angle Upon Zener diode 24 being rendered conductive, current flows through the circuit of the collector 26c and the emitter 26a of the first control transistor 26. As a result of conduction .of the first control transistor 26, base current flows in the second control transistor 27 by Way of the resistor 28 and the collector 26c and the emitter 26a of the first control transistor 26, resulting in the flow of current through the collector 270 of the transistor 27. Consequently, the potential difiference across the resistor 29 becomes greater to abruptly raise the potential at the base 30b of the igniting transistor 30 which is thereby out off. When, therefore, an arrangement is made so that the igniting transistor 30 is normally kept in its conducting state except at the time of ignition, the igniting transistor 30 is cut off at the point where ignition is desired. Upon this occurrence, primary current flowing in the ignition coil 33 connected in series with the igniting transistor 30 is abruptly interrupted to develop a high voltage in the secondary coil 32 of the ignition coil 33.

A contactless ignition device according to the present invention is quite advantageous in that there is almost no ignition lag since the Hall electromotive force V is generated in accordance with the igniting position of the engine by the Hall element of the igniting position detecting means 6 disposed in the rotating magnetic field. A further advantage is that the engine can stably be ignited at both high and low speeds because the Hall electromotive force V of a predetermined value can always be developed independently of the rotational speed of the rotor 7. A still further advantage is that the igniting position can automatically be advanced as the engine speed gets higher. This occurs because the smallsized electric generator 2 whose output is variable in response to the engine revolution is utilized to control the control current I for the Hall element 15 to thereby control the Hall electromotive force of the Hall element 15 and to regulate the operating point of the ignition control means 23. Therefore, the ignition device of the present invention is quite free from the prior difiiculty of obtaining a pro er igniting position due to friction or the like in a conventional igniting position advancing means of mechanical type, and is effective to simultaneously detect the igniting position of the engine and actuate the automatic igniting position advancing means.

In FIG. 5, there is shown another embodiment of the present invention which can attain an effect substantially similar to that attained by the embodiment shown in FIGS. 1-3. In FIG. 5, reference numeral 37 designates automatic igniting position advancing means which includes therein a small-sized electric generator 38 whose output is variable in response to any change in the revolution of the engine. The generator 38 has its power generating coil 39 connected to a smoothing circuit 41 by way of rectifiers 40.

Reference numeral 42 designates igniting position detecting means which includes therein a Hall element 43 disposed in a magnetic field rotating in synchronism with the revolution of the engine and a transistor 46, the emitter 46c and the base 46b of which are connected with output terminals 44 and 45 of the Hall element 43, respectively. One of control current terminals 47 of the Hall element 43 is connected with the other control current terminal 48 by way of a battery 49, the smoothing condenser 41 and a rheostat 50.

An igniting position regulating means 51 is provided, and is connected to transistor 46. The collector 46c of the transistor-46 is connected with the base 521) of a first transistor 52 provided in igniting position regulating means 51. The first transistor 52 is associated with a rheostat 53, a resistor 54 and an emitter resistance 55 and is so set that its collector 52c is cut off from the emitter 52c when a voltage at the rheostat 53 exceeds a predetermined voltage V A second transistor 56 also comprises a part of the igniting position regulating means 51. The transistor 56 is disposed in a manner that its emitter 562 is connected with the emitter resistance 55 in common with the emitter 522 of the first transistor 52. The'base 56b of the second transistor 56 is connected with the battery 49, by way of a resistor 57 and at the same time with the collector 520 of the first transistor 52 by way of a feedback resistor 59 with which has a condenser 58 connected in parallel therewith. The collector 520 of the first transistor 52 is in turn connected with the battery 49 by way of a resistor 60. The collector 56c of the second transistor 56 in the igniting position regulating means 51 is connected with the battery 49 by way of a resistor 61 or a regulating lamp 62.

Reference numeral 63 designates pulse generating means which is composed of a condenser 64 and a resistor 65 connected in series with the condenser 64. One terminal of the condenser 64 is connected with the collector 560 of the second transistor 56, while the other terminal is connected with the battery 49 by way of the resistor 65. 1

Reference numeral 66 designates ignition control means which includes therein two NPN-type transistors 67 and 63. The collector 67c of the transistor 67 is connected with the battery 49 by way of a resistor 69, while the emitter 67a is connected with the battery 49 by way of a resistor 70 in common with the emitter 68a of the transistor 68. The base 67b is connected with the collector tide of the transistor 68 by way of a resistor 71 and at the same time with the junction of the condenser 64 and the resistor 65 in the pulse generating means 63. The base 68b of the transistor 68 is connected with the collector 670 of the transistor 67 by way of a condenser 72 and at the same time with the battery 49 by way of a resistor 73. The collector 680 of the transistor 68 is connected with the battery 49 by way of a resistor 74.

There are two igniting transistors 75 and 76. The base 75b of the igniting transistor 75 is connected with the collector 63c of the transistor 68 in the ignition control means 66 by way of a base resistance 77, while the emitter 75e and the collector 75c are connected with the base 76b and the collector 76c of the transistor 76, respectively. The emitter 76:: of the transistor 76 is connected with the battery 49 by way of an emitter resistance 78, and the collector 760 is connected with the battery 49 by way of the primary coil 82 of an ignition coil 31. The secondary coil 79 which is inductively coupled to primary coil 82 is connected with an ignition plug 80. The emitter 76e and the collector 760 of the igniting transistor 76 are connected with opposite terminals of a transistor protective diode 83 with which a condenser 84 is connected in parallel.

In the contactless ignition device shown in FIGURE 5, the Hall element 43 in the igniting position detecting means 42 is disposed in the pulsed magnetic field produced in association with the revolution of the engine, and in which the magnetic flux density is subject to variation to thereby vary the igniting position of the engine. The pulsed magnetic field develops the Hall electromotive force V which is constant with respect to an angular position 6 irrespective of the number of revolutions of the engine, as shown by a curve A in FIG. 6. The output of the Hall element 43 is supplied to the base 52b of the first transistor 52 in the igniting position regulating means 51. As described in the foregoing, the first transistor 52 is so set that conduction betwen its emitter 52e and collector 520 is interrupted when a voltage across the rheostat 53 exceeds a predetermined value V Therefore, the transistor 52 is driven to its cut off state whenever the Hall electromotive force V of the Hall element 43, which is amplified by the transistor 46 and applied across the rheostat 53, exceeds the predetermined voltage V in FIG. '6.

Since the second transistor 56 in the igniting position regulating means 51 is preliminarily arranged so that it takes its cut-off state when the first transistor 52 is in its conducting state, tendency of the transistor 52 towards being driven to its cut-01f state by the voltage applied across the rheostat 53 is more and more accelerated by the feedback condenser 58 and the resistor 59, and thus the transistor 52 is abruptly driven to its cut-off state. On the other hand, the second transistor 56 forming a pair with this transistor 52 is quickly driven to its conducting state and is stabilized once it tends to take its conducting state.

When, therefore, the resistor 61 is connected with the collector 56c of the transistor 56, it constitutes the output terminal of the igniting position regulating means 51, and the voltage appearing across the resistor 61 takes the form of a square wave as shown by a line B in FIG. 6. The wave form of the output from the igniting position regulating means 51 is differentiated by the condenser '64 and the resistor 65 of the pulse generating means 63 connected with the resistor 61 and is thereby converted into a trigger signal, which is supplied to the ignition control means 66 which acts as a monostable multivibrator by the provision of the transistors 67 and 68. The transistors 67 and 68 of the ignition control means 66 form a pair and are arranged to be alternately cut off so that one of the transistors 68 is in its conducting state when the other transistor 67 is in its cut-off state. Then when the trigger signal by the pulse generating means 63 is applied to the ignition control means 66, the operative states of the transistors in the ignition control means 66 are reversed and now the transistor 68 is driven to its cut-off state and the transistor 67 to its conducting state. Duration of the cut-off state of the transistor 68 is 1:0.69 C.R. second which is determined by the condenser 72 and the resistor 73 connected with the base 68b of the transistor 68. Thus, the transistor 68 can always be maintained in its cut-ofi. state for a definite time. The cut-otf of the transistor 68 in the ignition control means 66 results in abrupt cut-off of a pair of igniting semi-conductors comprised by the igniting transistors 75 and 76. The transistors 75 and 76 normally supply current to the primary coil 82 of the ignition coil '81 by way of the emitter 76c and the collector 76c, and pulses at high voltage are thereby induced in the secondary coil 79 of the ignition coil 81 upon cut-off of transistors '75 and 76 to generate sparks between a spark gap in the ignition plug 80.

According to the above arrangement, the engine is ignited at the position when the Hall electromotive force V of the Hall element 43 in the igniting position detecting means 42 exceeds the predetermined voltage V Therefore, by replacing the resistor 61 in the igniting position regulating means 51 by the lamp 62, the igniting position of the engine can be ascertained by the lighting of the lamp 62 because the igniting position of the engine corresponds to a point at which the deenergized lamp 62 is energized, that is, a rising point of the line B in FIG. 6.

In the igniting position detecting means 42 having therein the Hall element 43, the value of the control current I supplied to the Hall element 43 can easily be varied by varying the resistance value of the rheostat 50 and thus the value of the Hall electromotive force V of the Hall element 43 can be shifted for example, from the curve A to a curve C in FIG. 6. As a result, the igniting position can be shifted from 6 to 6 in FIG. 6, with the set voltage V of the igniting position regulating means 51 kept fixed. The igniting position can likewise be shifted from 0 to 0 when the set voltage V of the igniting position regulating means 51 is varied to V by varying the resistance of the rheostat 53, with the control current I supplied to the Hall element 42 Further, the operating point of the igniting position regulating means 51 can easily be detected by employing the lamp '62 in lieu of the resistor 61 disposed at the output end of the igniting position regulating means 51 which is actuated whenever the output of the igniting position detecting means 42 exceeds the predetermined voltage V Therefore, by suitably regulating the control current I for the Hall element 43 or the set voltage V of the regulating means 51, the revolving angle 6 of the magnetic field rotating in association with the revolution of the engine can be regulated as desired to thereby regulate the igniting position. Thus, the effect similar to that obtained with the first embodiment of this invention can be obtained plus the additional control provided by rheostat 53.

From the foregoing description, it can be appreciated that the present invention provides new and improved ignition devices of the contactless type which use a Hall element to develop a definite electromotive force irrespecu tive of the rotational speed of the engine. The definite electromotive force is then used to trigger the ignition pulse produced in the ignition coil. Further, the invention provides means including an electric generator WhOSC output is variable in proportion to the engine speed, and which is connected across the control current terminals of the Hall element for automatically advancing the ig niting position in association with increases in the rota tional speed of the engine. Additionally, the igniting position regulating means are provided having a pair of transistors whose conducting state abruptly varies at a voltage more than a predetermined value. A rheostat is provided for controlling the voltage level at which this conducting state abruptly changes, and hence provides an additional element of control over the operation of the ignition device.

Having described two embodiments of a new and improved contactless ignition device adapted for automotive vehicles and the like, other variations and adaptations of the ignition device will be suggested to those skilled in the art in the light of the above teachings. It is therefor to be understood that any such changes or modifications in the particular embodiments of the invention described are considered to fall within the scope of the invention as defined by the appended claims.

What is claimed is:

1. A contactless ignition device adapted for automotive vehicles and the like comprising igniting position detecting means including a Hall element having input terminals and output terminals and disposed in a magnetic field produced in synchronism with the revolution of the engine, the density of the magnetic fiux producing said magnetic field being variable at the fringes thereof for varying the igniting position of the engine, means for applying an adjustable control current to the input terminals of the Hall element an igniting semi-conductor, an ignition coil energized by said igniting semi-conductor, and ignition control means operatively coupled to the output terminals of said Hall element and to the input of the igniting semi-conductor for controlling conduction through said igniting semi-conductor to thereby control the time of production of an ignition spark by said ignition coil.

2. A contactless ignition device according to claim 1, further including igniting position advancing means com,- prised by an electric generator whose output is variable in proportion to the revolution of the engine, said means being connected with across the control current input terminals of said Hall element in said igniting position detecting means for thereby controlling the output of said igniting position detecting means in accordance with the speed of the engine. I

3. A contactless ignition device according to claim 2 in which said H-all element in said igniting position detecting means is held between supporting blocks of low magnetic reluctance material, and pole pieces are provided in a rotary body rotating in synchronism with the revolution of the engine, said pole pieces being brought during rotation to a position opposite the supporting blocks to form a closed magnetic path through said Hall element.

4. A contactless ignition device according to claim 3, further comprising igniting position regulating means having a pair of transistors Whose conducting state is abruptly varied by a voltage appearing at the output terminal of said igniting position detecting means, and pulse generating means for supplying the output of said igniting position regulating means to said ignition control means for thereby controlling said igniting semi-conductor.

5. A contactless ignition device according to claim 4, further comprising a variable impedance element coupled to the input of said pair of transistors for controlling the voltage level at which their conducting state is abruptly varied.

6. A contactless ignition device according to claim 1, further comprising igniting positionregulating means having a pair of transistors whose conducting state is abruptly varied by a voltage appearing at the output terminal of said igniting position detecting means, pulse-generating means for supplying the output of said igniting position regulating means to said ignition control means for thereby controlling said igniting semi-conductor, and a variable impedance element coupled to the input of said pair of transistors for controlling the voltage level at which their conducting state is abruptly varied.

References Cited by the Examiner UNITED STATES PATENTS Yetter 123-148 Sichling et a1. 123148 Sekine et a1. Burig et a1. Short et a1. 123148 MARK NEWMAN, Primary Examiner.

LAWRENCE M. GOODRIDGE, Examiner. 

1. A CONTACTLESS IGNITION DEVICE ADAPTED FOR AUTOMOTIVE VEHICLESD AND THE LIKE COMPRISING IGNITING POSITION DETECTING MEANS INCLUDING A HALL ELEMENT HAVING INPUT TERMINALS AND OUTPUT TERMINALS AND DISPOSED IN A MAGNETIC FIELD PRODUCED IN SYNCHRONISM WITH THE REVOLUTION OF THE ENGINE, THE DENSITY OF THE MAGNETIC FLUX PRODUCING SAID MAGNETIC FIELD BEING VARIABLE AT THE FRINGES THEREOF FOR VARYING THE IGNITING POSITION OF THE ENGINE, MEANS FOR APPLYING AN ADJUSTABLE CONTROL CURRENT TO THE INPUT TERMINALS OF THE HALL ELEMENT AN IGNITING SEMI-CONDUCTOR, AN IGNITION COIL ENERGIZED BY SAID IGNITING SEMI-CONDUCTOR, AND IGNITION CONTROL MEANS OPERATIVELY COUPLED TO THE OUTPUT TERMINALS OF SAID HALL ELEMENT AND TO THE INPUT OF THE IGNITING SEMI-CONDUCTOR FOR CONTROLLING CONDUCTION THROUGH SAID IGNITING SEMI-CONDUCTOR TO THEREBY CONTROL THE TIME OF PRODUCTION OF AN IGNITION SPARK BY SAID IGNITION COIL. 